Westphalian

The predominant types of fossils found in the Westphalian strata of South Yorkshire
belong to three general groups, each representing the ecosystem associated with one
of three principal paleo-environments, namely: low-lying, swampy land areas adjacent
to meandering river channels; waterlogged swamps or shallow, deltaic lakes; and the
shallow sea bed formed from the previous two environments when the sea level rose
periodically to flood extensive areas of river delta and coastal plain before
retreating again. These groups are as follows:

Plants
Various types of fern foliage, such as Neuropteris and Pecopteris,
make up the most common plant fossils of the Westphalian. In addition, swamp-loving
lycopods, like Lepidodendon and Sigillaria, and the giant horse-tail,
Calamites, have been recorded in several places. Primitive gymnosperms, such as
Cordaites, represent plants living in drier conditions on higher ground.
See:
Lepidodendron

Non-marine fauna
Bands of mussel shells occur at several horizons and are distinguished by evolutionary
adaptations over time. These fresh water bivalves probably lived in a vertical position,
buried beneath the surface of muddy sediment below shallow bodies of standing water.
Ostracods, small crustaceans, serpulids and occasional fish remains have also been recorded.

Marine fauna
Representing a relative rise in sea level, the 'marine bands' contain salt water
marker fossils which have been of significant value in determining stratigraphy. Marine
Bands contain brachiopods, bivalves, gastropods, ostracods and crinoids, but of particular
interest are the cephalopods, such as goniatites, which are restricted to major incursions.
The brachiopod, Lingula, is common throughout and may be associated with foraminifera,
conodonts and sponge spicules.